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de Rham, C., & Motohashi, H. (2017). Caustics for spherical waves. Phys. Rev. D, 95(6), 064008–13pp.
Abstract: We study the development of caustics in shift-symmetric scalar field theories by focusing on simple waves with an SO(p)-symmetry in an arbitrary number of space dimensions. We show that the pure Galileon, the DBI-Galileon, and the extreme-relativistic Galileon naturally emerge as the unique set of caustic-free theories, highlighting a link between the caustic-free condition for simple SO(p)-waves and the existence of either a global Galilean symmetry or a global (extreme-) relativistic Galilean symmetry.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2017). Cross sections for the reactions e(+)e(-) -> (KSKL0)-K-0 pi(0), (KSKL0)-K-0 eta, and (KSKL0)-K-0 pi(0)pi(0) from events with initial-state radiation. Phys. Rev. D, 95(5), 052001–16pp.
Abstract: We study the processes e(+)e(-) -> (KSKL0)-K-0 pi(0)gamma, (KSKL0)-K-0 eta gamma, and (KSKL0)-K-0 pi(0)pi(0)gamma, where the photon is radiated from the initial state, providing cross section measurements for the hadronic final states over a continuum of center-of-mass energies. The results are based on 469 fb(-1) of data collected at or near the psi(4S) resonance with the BABAR detector at SLAC. We present the first measurements of the e(+)e(-) -> (KSKL0)-K-0 pi(0), (KSKL0)-K-0 eta, and (KSKL0)-K-0 pi(0)pi(0) cross sections up to a center-of-mass energy of 4 GeV and study their intermediate resonance structures. We observe J/psi decays to all of these final states for the first time, present measurements of their J/psi branching fractions, and search for psi(2S)decays.
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Miyahara, K., Hyodo, T., Oka, M., Nieves, J., & Oset, E. (2017). Theoretical study of the Xi(1620) and Xi(1690) resonances in Xi(c)-> pi(+) MB decays. Phys. Rev. C, 95(3), 035212–12pp.
Abstract: Nonleptonic weak decays of Xi(c) into pi(+) and a meson (M)-baryon (B) final state, MB, are analyzed from the viewpoint of probing S = -2 baryon resonances, i.e., Xi(1620) and Xi(1690), of which spin-parity and other properties are not well known. We argue that the weak decay of Xi(c) is dominated by a single quark-line diagram, preferred by the Cabibbo-Kobayashi-Maskawa coefficient, color recombination factor, the diquark correlation, and the kinematical condition. The decay process has an advantage of being free from meson resonances in the p+ M invariantmass distribution. The invariant mass distribution of the meson-baryon final state is calculated with three different chiral unitary approaches, assuming that the Xi(1620) and Xi(1690) resonances have J(P) = 1/2(-). It is found that a clear peak for the Xi(1690) is seen in the pi Xi and K Lambda spectra. We also suggest that the ratios of the pi Xi, K Lambda, and K Sigma final states are useful to distinguish whether the peak is originated from the Xi(1690) resonance or it is a K Sigma threshold effect.
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PreSPEC and AGATA Collaborations(Ralet, D. et al), Domingo-Pardo, C., Gadea, A., & Huyuk, T. (2017). Lifetime measurement of neutron-rich even-even molybdenum isotopes. Phys. Rev. C, 95(3), 034320–11pp.
Abstract: Background: In the neutron-rich A approximate to 100 mass region, rapid shape changes as a function of nucleon number as well as coexistence of prolate, oblate, and triaxial shapes are predicted by various theoretical models. Lifetime measurements of excited levels in the molybdenum isotopes allow the determination of transitional quadrupole moments, which in turn provides structural information regarding the predicted shape change. Purpose: The present paper reports on the experimental setup, the method that allowed one to measure the lifetimes of excited states in even-even molybdenum isotopes from mass A = 100 up to mass A = 108, and the results that were obtained. Method: The isotopes of interest were populated by secondary knock-out reaction of neutron-rich nuclei separated and identified by the GSI fragment separator at relativistic beam energies and detected by the sensitive PreSPEC-AGATA experimental setup. The latter included the Lund-York-Cologne calorimeter for identification, tracking, and velocity measurement of ejectiles, and AGATA, an array of position sensitive segmented HPGe detectors, used to determine the interaction positions of the gamma ray enabling a precise Doppler correction. The lifetimes were determined with a relativistic version of the Doppler-shift-attenuation method using the systematic shift of the energy after Doppler correction of a gamma-ray transition with a known energy. This relativistic Doppler-shift-attenuation method allowed the determination of mean lifetimes from 2 to 250 ps. Results: Even-even molybdenum isotopes from mass A = 100 to A = 108 were studied. The decays of the low-lying states in the ground-state band were observed. In particular, two mean lifetimes were measured for the first time: tau = 29.7(-9.1)(+11.3) ps for the 4(+) state of Mo-108 and tau = 3.2(-0.7)(+ 0.7) ps for the 6(+) state of Mo-102. Conclusions: The reduced transition strengths B(E2), calculated from lifetimes measured in this experiment, compared to beyond-mean-field calculations, indicate a gradual shape transition in the chain of molybdenum isotopes when going from A = 100 to A = 108 with a maximum reached at N = 64. The transition probabilities decrease for Mo-108 which may be related to its well-pronounced triaxial shape indicated by the calculations.
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Bejarano, C., Olmo, G. J., & Rubiera-Garcia, D. (2017). What is a singular black hole beyond general relativity? Phys. Rev. D, 95(6), 064043–18pp.
Abstract: Exploring the characterization of singular black hole spacetimes, we study the relation between energy density, curvature invariants, and geodesic completeness using a quadratic f(R) gravity theory coupled to an anisotropic fluid. Working in a metric-affine approach, our models and solutions represent minimal extensions of general relativity (GR) in the sense that they rapidly recover the usual Reissner-Nordstrm solution from near the inner horizon outwards. The anisotropic fluid helps modify only the innermost geometry. Depending on the values and signs of two parameters on the gravitational and matter sectors, a breakdown of the correlations between the finiteness/ divergence of the energy density, the behavior of curvature invariants, and the (in) completeness of geodesics is obtained. We find a variety of configurations with and without wormholes, a case with a de Sitter interior, solutions that mimic nonlinear models of electrodynamics coupled to GR, and configurations with up to four horizons. Our results raise questions regarding what infinities, if any, a quantum version of these theories should regularize.
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Richard, J. M., Valcarce, A., & Vijande, J. (2017). String dynamics and metastability of all-heavy tetraquarks. Phys. Rev. D, 95(5), 054019–7pp.
Abstract: Multiquark states have been advocated to explain recent experimental data in the heavy-light sector, and there are already speculations about multiquarks containing only heavy quarks and antiquarks. With a rigorous treatment of the four-body problem in current quark models, full-charm (cc (c) over bar(c) over bar) and full-beauty(bb (b) over bar(b) over bar) tetraquarks are found to be unbound. Thus their stability should rely on more subtle effects that are not included in the simple picture of constituent quarks. The case of (bc (b) over bar(c) over bar) might be more favorable if the naive color-additive model of confinement is replaced by a string-inspired interaction.
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Abbas, G. (2017). Low scale left-right-right-left symmetry. Phys. Rev. D, 95(1), 015029–8pp.
Abstract: We propose an effective left-right-right-left model with a parity breaking scale around a few TeV. One of the main achievements of the model is that the mirror fermions as well as the mirror gauge sector simultaneously could be at TeV scale. It is shown that the most dangerous quadratic divergence of the SM Higgs boson involving the top quark in the loop is naturally suppressed, and begins at three loop. The model postpones the fine-tuning of the mass of the SM Higgs boson up to a sufficiently high scale. The model explains the smallness of the neutrino masses whether they are Dirac or Majorana. Furthermore, the strong CP phase is zero in this model.
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Hernandez, E., & Nieves, J. (2017). Neutrino-induced one-pion production revisited: The nu(mu)n -> mu(-)n pi(+) channel. Phys. Rev. D, 95(5), 053007–18pp.
Abstract: Understanding single pion production reactions on free nucleons is the first step towards a correct description of these processes in nuclei, which are important for signal and background contributions in current and near future accelerator neutrino oscillation experiments. In this work, we reanalyze our previous studies of neutrino-induced one-pion production on nucleons for outgoing pi N invariant masses below 1.4 GeV. Our motivation is to get a better description of the nu(mu)n -> mu(-)n pi(+) cross section, for which current theoretical models give values significantly below data. This channel is very sensitive to the crossed Delta(1232) contribution and thus, to spin 1/2 components in the Rarita-Schwinger Delta propagator. We show how these spin 1/2 components are nonpropagating and give rise to contact interactions. In this context, we point out that the discrepancy with experiment might be corrected by the addition of appropriate extra contact terms and argue that this procedure will provide a natural solution to the nu(mu)n -> mu(-)n pi(+) puzzle. To keep our model simple, in this work, we propose to change the strength of the spin 1/2 components in the. propagator and use the nu(mu)n -> mu(-)n pi(+) data to constraint its value. With this modification, we now find a good reproduction of the nu(mu)n -> mu(-)n pi(+) cross section without affecting the good results previously obtained for the other channels. We also explore how this change in the. propagator affects our predictions for pion photoproduction and find also a better agreement with experiment than with the previous model.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., et al. (2017). Measurements of charm mixing and CP violation using D-0 -> K-+/-pi(-/+) decays. Phys. Rev. D, 95(5), 052004–14pp.
Abstract: Measurements of charm mixing and CP violation parameters from the decay-time-dependent ratio of D-0 -> K+pi(-) to D-0 -> K-pi(+) decay rates and the charge-conjugate ratio are reported. The analysis uses (B) over bar -> D*(+) μX-, and charge-conjugate decays, where D *(+) -> D-0 pi(+), and D-0 -> K-+/-pi(-/+). The pp collision data are recorded by the LHCb experiment at center-of-mass energies root s = 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb(-1). The data are analyzed under three hypotheses: (i) mixing assuming CP symmetry, (ii) mixing assuming no direct CP violation in the Cabibbo-favored or doubly Cabibbo-suppressed decay amplitudes, and (iii) mixing allowing either direct CP violation and/or CP violation in the superpositions of flavor eigenstates defining the mass eigenstates. The data are also combined with those from a previous LHCb study of D-0 -> K pi decays from a disjoint set of D*(+) candidates produced directly in pp collisions. In all cases, the data are consistent with the hypothesis of CP symmetry.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., et al. (2017). Measurement of the B-+/- production asymmetry and the CP asymmetry in B-+/-> J/psi K-+/- decays. Phys. Rev. D, 95(5), 052005–13pp.
Abstract: The B-+/- meson production asymmetry in pp collisions is measured using B-+/- -> (D) over bar (0)pi(+) decays. The data were recorded by the LHCb experiment during Run 1 of the LHC at center- of- mass energies of ffiffiffi root s = 7 and 8 TeV. The production asymmetries, integrated over transverse momenta in the range 2 < p(T) < 30 GeV/c, and rapidities in the range 2.1 < y < 4.5 are measured to be A(prod)(B+, root s = 7 TeV) = (-0.41 +/- 0.49 +/- 0.10) x 10(- 2), A(prod)(B+, root s = 8 TeV = (- 0.53 +/- 0.31 +/- 0.10) x 10(-2), where the first uncertainties are statistical and the second are systematic. These production asymmetries are used to correct the raw asymmetries of (B+ -> J/psi K+) decays, thus allowing a measurement of the CP asymmetry, A(CP)(B+-> J/psi K+) = (0.09 +/- 0.27 +/- 0.07) x 10(-2)
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